The invention relates to digital tape drive data storage devices, and in particular, to a method and apparatus for unlocking the tape cartridge locking mechanism in a single reel tape cartridge when the tape cartridge is loaded into the tape drive.
It is a problem in industry standard DLT tape cartridges that the tape cartridge locking mechanism can fail to unlock during the tape cartridge loading sequence in a DLT tape drive. This failure results in the inability of the tape drive to pull the magnetic tape out of the tape cartridge and into the tape path.
Digital data is stored on magnetic tape media by tape drives utilizing a variety of designs, but in all cases, magnetic tape media is wound between a pair of tape reels as data is transferred to or from the magnetic tape media. In the art of data storage, the physical space required to store data is an important concern. To conserve space, tape drives often use a single reel tape cartridge design, which utilizes a supply reel located within a removable tape cartridge and a take-up reel located within the tape drive.
After the tape cartridge is inserted into the tape drive, the magnetic tape media must be loaded into the tape drive. The loading operation includes connecting the magnetic tape media to the take-up reel and winding the magnetic tape media to a start point or read position. Various methods have been employed to make this connection. FIG. 1 illustrates one such method wherein the magnetic tape media connects to the take-up reel via a buckle 100 between a tape cartridge leader 103 and a take-up leader 101. The tape cartridge leader 103 terminates the magnetic tape media at one end and is a strong flexible plastic strip that includes an ovular aperture 102 configured to mate with the take-up leader 101. The take-up leader 101 is a similar strong flexible plastic strip attached at one end to the take-up reel. The opposing end includes a stem 104 and a tab 105 designed to buckle with the ovular aperture 102 on the tape cartridge leader 103. During the buckling operation, a rotating catch connected to a load motor cooperates with a positioning lever to position the take-up leader 101 and the tape cartridge leader 103 for buckling. After the take-up leader 101 and the tape cartridge leader 103 are buckled, the catch is rotated out of the way to a loaded position and the buckle 100 is wound through a tape path until the magnetic tape media is in a read position relative to the tape head. Similarly, an unloading operation includes unwinding the take-up leader 101 and tape cartridge leader 103 back past the tape head, rotating the catch back to the unloaded position to disconnect the take-up leader 101 and the tape cartridge leader 103, and ejecting the tape cartridge from the tape drive.
Unfortunately, failures that cause the tape drive to malfunction can occur during the tape cartridge loading operation. One form of failure, referred to as a locking mechanism failure, occurs when the tape cartridge locking mechanism located within the tape cartridge does not completely rotate back to the unlocked position upon loading of the tape cartridge. When this occurs, the tape cartridge locking mechanism does not disconnect from the locking features on the tape reel, causing the tape reel to become stuck in the tape cartridge when rotation of the tape reel is attempted. Following a locking mechanism failure, the tape drive must eject the tape cartridge out of the tape drive.
Unfortunately, this problem is not easily solved since the operation of the tape cartridge locking mechanism, which retains the magnetic tape media in the tape cartridge is mechanically tied to a single unlock mechanism in the tape drive. During operation, the unlock mechanism attempts to release the tape cartridge locking mechanism and allow the tape reel to rotate and initiate the tape buckling operation described above. If the tape cartridge locking mechanism is stuck due to reverse rotation of the tape reel, the unlock mechanism in the tape drive is incapable of overcoming the force exerted on the tape cartridge locking mechanism by the tape reel.
The above described problems are solved and a technical advance achieved by the present method for unlocking a single reel tape cartridge locking mechanism in a tape cartridge load operation, which aid the release of the tape cartridge locking mechanism by manipulating the supply reel motor which is engaged to the single reel tape cartridge in a manner that causes the stuck tape cartridge locking mechanism to release. In order to aid the release of the tape cartridge locking mechanism during the tape cartridge loading procedure, the supply reel motor is operated cyclically to cause the supply reel to vibrate. This vibration is held for a predetermined period of time. At the end of the vibration cycle, the tape drive attempts to pull the tape cartridge leader out of the tape cartridge. If the tape drive again detects that the tape cartridge locking mechanism is not released, it repeats the vibration sequence. The tape drive can execute a predetermined number of attempts to release the tape cartridge locking mechanism in this manner. If this process is not successful, then the tape drive logs a failure and rejects the tape cartridge by ejecting the tape cartridge from the tape drive.